Traditional non-invasive blood pressure monitoring devices operate by inflating a cuff to a pressure well above a patient's systolic blood pressure. Because the systolic pressure is usually not know prior to inflation, the cuff must be inflated to such a high pressure to ensure that the patient's arterial blood flow is completely occluded. Once well above systole, the cuff is deflated and the systolic and diastolic pressures are calculated based on signals provided during cuff deflation.
Some methods have been developed to estimate blood pressures during cuff inflation. These methods, however, are generally inaccurate and/or slow. Consequently, such methods cannot provide a commercially useful determination of systolic pressure that must meet certain regulatory standards.
More recently, a suprasystolic measurement technique has been developed, as described by U.S. Pat. No. 6,994,675. This technique includes inflating a cuff to a “suprasystolic pressure,” about 10-40 mmHg above a patient's systolic pressure. Suprasystolic pressure can be maintained while signals from the occluded artery are collected. These signals are processed to determine a number of hemodynamic parameters, such as, for example, aortic compliance.
Current suprasystolic methods require determining a patient's systolic blood pressure prior to inflating the cuff because the suprasystolic pressure is directly proportional to the systolic pressure. As described above, current methods for accurately determining systolic pressure rely on inflating and then deflating a cuff. Thereafter, the cuff is re-inflated to a suprasystolic pressure (i.e., about 10-40 mmHg above systole). Such repeated inflation and deflation of the cuff takes additional time and exposes the patient to the additional discomfort.
The present disclosure is directed to systems and methods for providing a suprasystolic measurement in less time and with less patient discomfort than prior techniques. In one exemplary embodiment, a patient's systolic pressure can be determined during cuff inflation. Following inflation, the cuff can be maintained at a suprasystolic pressure determined by the systolic pressure. During this suprasystolic phase, signals from the patient can be measured and analyzed to determine one or more hemodynamic parameters. Thus, data obtained during an inflationary, or dynamic phase, of a pressure cycle may be used in real time to determine if and how a suprasystolic measurement should be conducted. Combining a systolic pressure determination and suprasystolic measurement into a single pressure cycle can reduce cycle time and minimize patient discomfort.